A NEW TOOL TO OBJECTIVE ASSESSMENT OF ROTATIONAL INSTABILITY AND ACL/PCL DEFICIENT KNEES INSIDE MAGNETIC RESONANCE IMAGING OR CT SCAN.
Porto Knee Testing Device

WE BELIEVE THAT THIS IS A USEFUL, RELIABLE DEVICE TO QUANTIFY ANTEROPOSTERIOR, POSTEROANTERIOR AND ROTATIONAL INSTABILITY OF THE KNEE.

Anterior cruciate ligament (ACL), posterior cruciate ligament (PCL) and rotation instabilities injuries remain an important cause of orthopedic surgery1. A long way has been traveled since the eighties, with improvements in surgical techniques, grafts choice and management or fixation devices.
 
Recently the advent of anatomic concept started a new era. It is now consensually recognized that ACL has two functional bundles, the anteromedial bundle (mainly resisting anterior tibial translation) and posterolateral bundle (primarily restrains against rotational instability)2.
Aiming for more anatomic ACL and PCL reconstruction new technical approaches have been developed to improve upon the results of single-bundle or double bundle reconstruction3,4.
Nowadays patients have higher expectations and surgeon’s goal remains restoring normal structure and function of the knee and preventing the future development of arthritis.

 

Porto Knee Testing Device

 

Porto Knee Testing Device

Manual examinations are influenced by surgeon’s training5, and although the pivot shift test is a better predictor of clinical outcomes than any uniplanar examination maneuver, the Lachman test remains the most commonly used 6-8.

Nevertheless the limitations of the pivot-shift test and reverse pivot shift, particularly in an awake patient must be considered.
We agree with Irrganng et al: “A simple clinically applicable tool, similar to the KT-1000 arthrometer, that could be used to reliably quantify rotational laxity of the knee needs to be developed”9.

Since the first report10, the KT-1000 laximeter (Medmetric,San Diego, CA, USA) is the most widely used knee ligament testing system because it is an easy-to-use device and still remains the reference instrument against which are tested new devices11. However this is an operator-dependent device, doesn’t measure rotation and has a known propensity to induce false negative results and questionable reproducibility12,13.
The ideal tool to evaluate the knee should be a mean to assess both the “anatomy” and the “function” in the same examination. This led us to develop a method to objectively measure the antero-posterior translation and rotational instability during MRI – the Porto Knee Testing Device (PKTD®).
This new device is able to measure antero-posterior and rotatory instability of the knee, while doing a MRI/CT-scan examination.